Acer V3-771g-9809 cannot shutdown!

After upgrading BIOS (Insyde V1.2 to V2.21), I couldn't install windows 7 on UEFI & AHCI mode anymore (I added an SSD to it.) I had to do hard reset several times, and then suddenly my laptop froze when I shut it down. This keeps happening for a week now. The laptop freezes every time I try to turn it off normally, even in BIOS menu. Screen, usb ports,wifi light, and sounds are off, but the main power light, the power button light, and the fan is still on. I can still restart; it does turn off and then turn back on, but it still freezes after screen is off for about 20s before completely turn off and then turn back on. (This is the only problem. My laptop works just fine but this error.)

Anyone has any idea? I really want to fix it myself. My last option would be sending it back to acer through acer warranty; however, I need this laptop for studying.

How can I flash the bios back? I have looked at almost all posts on the forum that I can understand, but it didn't help (I already tried flashing using usb + unplugged power cord + Fn & Esc, changed the name around, but they did not work.)